Coreless induction heater



01:1. 17, 1939. B. RONAY 2,176,103

CORELES S INDUCTION HEATER Filed Dec. 14, 1938 INVENTOR BELA RONAY ATTORNEY- Patented Oct. 17, 1939 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 4 in the parts and combinations thereof hereinafter set forth and claimed, with the understanding that the several necessary elements constituting the same may be varied in proportion and arrangement without departing from the nature and scope of the invention, as defined in the appended claims.

In order to make the invention more clearly understood, ther are shown in the accompanying drawing, means for carrying the invention into practical use, without limiting the improvements in their useful application to the particular construction, which, for the purpose of explanation, have been made the subject of illustration.

In the accompanying drawing:

Fig. 1 is an end elevational view of a coreless heater embodying the invention;

Fig. 2 is a plan view of the structure shown in Fig. 1; and

Fig. 3 is a fragmentary sectional view through one of the tierods.

Referring to the drawing, a coreless induction heater constructed in accordance with the invention is shown as comprising a plurality of conductors Ill of substantially U-shape and having vertically extending legs ii and i2 secured together by tie rods 13 and M in spaced parallel relation and together forming a group embracing a pipe IE to be heated. The legs ii and I 2 of the conductors It on opposite ends of the group are formed with transversely extending portions or flanges l6 and II, respectively, to which cables l8 and I9. are secured leading to the secondary windings of a power transformer. The conductors III are preferably constructed of copper tubing flattened to a total thickness of three times that of the walls so as to provide an air duct therethrough for cooling purposes. The conductors III are insulated from the tie rods l3 and M by tubular members 20 (Fig. 3) and from one another by spacing washers 2|. The

end legs ll of the conductors ill are slotted to receive a plurality of connecting straps or bringing members 22. These straps are pivotally connected in the slots of the legs I l of 'the conductors i0 and are offset angularly with respect to the axis of the pipe l5 for frictional engagement with the slots in the legs I2 of the next adjacent conductor in the manner of a knife switch. In this manner the assembly or group is substantially the same as a helical coil in that electric current flows through the conductors l0 and straps 20 successively, so as to induce a current in the pipe l5, acting as a core, and heat the same.

The pipe I5 is properly centered by adjusting screws 23 which are threaded into the rods l3 and I4 adjacent to the ends thereof. The pipe l5 may be surrounded with an asbestos packing 24, if desired. In the drawing, the pipe I5 is shown as having a drain line 25 welded therein which is also included in the portion of the pipe being heated by not closing the strap 22 adjacent to the branch pipe. In this adaptation of the device the circuit is completed through the heater by means of a flexible jumper 26, one end of which is fixed to a plate 21 which is inserted in the slotted end of the conductor on one side of the branch pipe and the other end of which may be attached to the strap 22 on the other side of the pipe 25.

if it is desired to use the apparatus as a preheater, it may be set in position and with the blades open the joint may be tacked. The blades 22 are then closed and the current turned on to preheat the pipe ends. When the desired preheat temperature is reached, the current may be cut off, th blades opened and the welding started at the portion bored by opening the blades. On completion of this portion of the weld, the centering screws may be loosened and the apparatus rotated to bare the adjacent quadrant. This may be repeated until the entire weld is completed. Thereafter, the blades may be closed and the postheat treatment may begin taking advantage of the heat accumulation in the joint.

The fact that each turn is individually closed by a blade makes the apparatus suitable for use to preheat and postheat other than straight butt joints; In case a small diameter drain line 25 is welded into a large diameter steam main l5, as shown in the drawing, the connection, because of the extreme localization of the weld, causes the development of residual stresses of a higher order. Such welds must be stress relieved; and if the tube is of an air-hardening low alloy steel, the-Joint must be preheated. I

It will be understood that the above description and accompanying drawing comprehend only the general and preferred embodiment of the inyention, and that various other changes in the lated from one another. and a plurality oi straps pivotally connected to one leg of each of said conductors and cited; anaularly with respect thereto for electrical contact with the opposite leg or an adjacent conductor to complete an electric circuit through said group and to embrace a pipe beinzheated.

2.- a corelessinduction heater m pipe jointsand the like comprising a group of flattened tubular conductors of substantially U-shape secured together in spaced parallel relation and electrically insulated from one another. a plurality of straps pivotally connected to one leg of each of said conductors and oflset angularly with respect thereto for electrical contact with the opposite leg of an adjacent conductor to complete an electric circuit through said group and to embrace a pipe being heated, and means for positioning the pipe within said heater.

BELA RONAY. 

